1. Field of the Invention
This invention is concerned with compositions and processes for the dispersing of oil spillages. More specifically, the invention relates to the dispersal of oil spillages using aqueous emulsifier compositions prepared by the on-site dilution of suitable concentrates consisting of an emulsifier, a solvent and a pour-point depressant.
2. Description of prior art
There have been considerable advances in the art of treating oil spillages since the Torrey Canyon disaster off Cornwall in 1967. For example, it soon became apparent that the compositions used caused undesirable damage to marine life, primarily because of the extreme toxicity of the aromatic solvents used therein. The subsequent replacement of the aromatic solvents by an odourless kerosene containing less than 3% aromatics and/or isopropanol greatly reduced the toxic hazard. The newer solvents, however, in themselves produced problems; they were relatively volatile, and led to explosion and fire hazards. In addition they were relatively poor solvents for the active ingredient (which in general was the mono oleic acid ester of a polyethylene glycol), and their poor solvent power meant that compositions prepared therefrom tended to separate into two layers on storage as well as being unable to hold sufficient of the active ingredient. As a result, considerable stocks and storage facilities were necessary, and the boats carrying out the spraying operation had only short working periods at sea, and needed constant replenishing with the dispersant.
More recently, proposals have been made for detergent concentrates which may be diluted on site with sea water or fresh water. Unfortunately, while overcoming many of the problems of the earlier compositions, the newer concentrates have proved rather less effective in actually dispersing the oil at sea. Processes employing compositions of the kind described above are described and claimed in a number of earlier Patent Specifications. British Specification (Shell) No. 1,280,259 is believed to be the first to point to the use of aliphatic carboxylic acid polyoxyethylene glycol mono-esters as the emulsifier, but suggests that these materials should be dissolved in hydrocarbon solvents (such paraffins or naphthenes) containing up to 10 wt. % aromatic material. In the later I.C.I. British Specification No. 1,338,391 there is described the use of similar emulsifying fatty acid polyoxyalkylene glycol mono-esters, but again it is suggested that the solvents to be used with these emulsifiers should be hydrocarbons (including aromatic materials) or simple alcohols such as isopropanol. A very similar disclosure is made in I.C.I.'s British Specification No. 1,338,385 and again in I.C.I.'s British Specification No. 1,342,591.
BP British Specification No. 1,399,860 describes the use of emulsifying fatty acid polyoxyethylene glycol esters, but again suggests that these emulsifiers should be used in conjunction with a hydrocarbon solvent, while I.C.I.'s British Specification No. 1,343,401 is another describing the use of materials very similar to those mentioned in the aforesaid British Specification No. 1,338,391.
In Dasic's British Specification No. 1,404,684 there is one of the first disclosures of the use, as emulsifiers, of mixtures of fatty acid polyoxyalkylene glycol esters together with fatty acid sorbitan esters. However, even here it is still suggested that the solvent to be employed is a hydrocarbon, albeit with less than 3 wt. % aromatic material. This Specification also points out the desirability of using a cloud point depressant (pour point depressant).
Finally, Canevari's (Esso's) U.S. Pat. No. 3,793,218 describes in detail the use of multi-part emulsifier compositions containing, among other possible components, certain fatty acid sorbitan esters, certain sorbitan/polyoxyalkylene glycol adducts, and certain dialkyl sulphosuccinate salts. But again it is suggested that these emulsifiers should be used together with a solvent which is a hydrocarbon.